# Learning-mediated plasticity in cortical feedback projections to the olfactory bulb

> **NIH NIH R00** · UNIVERSITY OF ILLINOIS AT CHICAGO · 2024 · $92,614

## Abstract

PROJECT SUMMARY/ABSTRACT
 To reliably encode information about the environment, neurons must modify their activity profiles and even
connectivity to accurately interpret complex stimuli. Cortical feedback projections to the olfactory bulb are
uniquely positioned at the interface between detection-based processing that is driven by sensory input and
analytical processing occurring in the piriform cortex. This arrangement makes these projections an ideal target
to study how learning reshapes neuronal activity profiles. I have developed an approach that will allow for a
comprehensive analysis of the axonal activity of principal neurons in the piriform cortex, while mice learn a task
requiring them to identify a specific odor embedded in complex mixtures, thereby providing unique insight into
olfactory scene analysis. My approach will also provide a detailed analysis of the connectivity between cortical
axons and their postsynaptic targets in the olfactory bulb, which will reveal how the olfactory bulb integrates
processed information from the piriform cortex. The hypothesis I will test is that learning reshapes cortico-fugal
input to the olfactory bulb, leading to enhanced odor-scene segmentation through the disambiguation of
olfactory bulb output neuron activity profiles. The outcomes of these studies will provide novel insight into how
the brain updates its stimulus-encoding scheme from a synthetic to an analytical representation of a stimulus
environment. The studies proposed here are novel technically as well as conceptually, and the results will be
broadly applicable to other sensory systems. In Aim 1, I will characterize how learning shapes the activity of
cortical feedback projections to the olfactory bulb. Aim 2 will determine how the synaptic strength and number
of cortical inputs to individual olfactory modules are updated during learning. Finally, Aim 3 will determine how
cortical input shapes the activity profiles of bulbar output neurons. The training phase of this award was
conducted at Harvard University in the laboratories of Prof. Venkatesh Murthy and Prof. Naoshige Uchida. This
award will support a Diversity Fellow in my independent laboratory at the University of Illinois at Chicago to
provide her technical skills in the laboratory, academic preparation, and professional development necessary to
successfully apply to top graduate programs.

## Key facts

- **NIH application ID:** 11002568
- **Project number:** 3R00DC017754-05S1
- **Recipient organization:** UNIVERSITY OF ILLINOIS AT CHICAGO
- **Principal Investigator:** Joseph Donald Zak
- **Activity code:** R00 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $92,614
- **Award type:** 3
- **Project period:** 2020-01-01 → 2026-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11002568

## Citation

> US National Institutes of Health, RePORTER application 11002568, Learning-mediated plasticity in cortical feedback projections to the olfactory bulb (3R00DC017754-05S1). Retrieved via AI Analytics 2026-06-14 from https://api.ai-analytics.org/grant/nih/11002568. Licensed CC0.

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